WASHINGTON — To celebrate her selection as a presidential debate moderator, CNN staff filled Candy Crowley's office with balloons and posed life-sized cardboard cutouts of President Obama and former governor Mitt Romney facing her desk.

Two months later, the cardboard cutouts are still there, adorned with necklaces and scarves and pushed into a corner. The three-dimensional versions will face Crowley on Tuesday as she manages a town-hall-style debate, the loosest format among presidential debates and possibly the toughest task for the moderator.

Crowley will choose which questions get asked by the 80-member audience and ask follow-up questions herself, while watching three clocks to keep track of candidates' speaking time — all the while hoping nobody decides to ask a question about what pizza topping the candidates prefer. (A national pizza chain has offered a prize for doing so.)

No wonder Crowley is studying hard, rehearsing, and feeling "slightly nauseous every morning.''

A 30-year veteran of presidential politics, Crowley, 63, is moderating for the first time in an election season where moderators are under greater-than-usual scrutiny. PBS' Jim Lehrer was excoriated for not intervening more often as Obama and Romney ran over their time limits. Conservative websites questioned vice-presidential debate moderator Martha Raddatz's objectivity because then-law student Barack Obama attended her wedding in 1991. And Carole Simpson, the ABC journalist who moderated the first town-hall-style debate 20 years ago, says that choosing a woman for this format means Crowley's being marginalized.

A town hall-style debate, she says, is "impossible to prepare for and completely required that you overprepare. (It is) really different from anything you've ever done before.''

A vegetarian who meditates twice a day, Crowley has even given up soft drinks (Diet Dr. Pepper). What's left is a lot of nervous joking. "I'm a non-drinker," she tells a visitor. "But I'm really thinking about it. I'm thinking that might be the way to go."

The guest list at her wedding more than 30 years ago, she says, consisted entirely of relatives, "and none of them pay the least bit of attention to politics." (She is no longer married.)

The audience at Hofstra University — 80 uncommitted voters from Long Island's Nassau County recruited by Gallup — will ask the questions, but Crowley will choose who asks them. She will know the questions in advance and call on the audience members. She, not the audience members, asks the follow-ups.

"This is about their questions, but you also want to use your knowledge to make (the candidates' responses) not the two-minute answers that they're practicing in their headquarters right now," she says.

She is "stuffing her head" with information on obvious subjects such as unemployment, taxes, Social Security and gas prices to come up with possible follow-up questions — "drill-down questions,'' she calls them — that she might ask. Not only is she soliciting questions of everyone she knows, she's getting reams of e-mail suggestions, including plenty of rants.

Many of the questions she receives, she says, are about state-level issues better suited to a governor's race. Many, while interesting, don't speak to larger issues that most people want to know about. Not all of them, she says, have to be about policy. "There are certain questions — and you know them when you see them — that can be revealing. The thought-provoking question, not the policy-provoking question, can be instructive about how the (candidates) handle things in general, their mindset about something or other."

At the same time, she will be keeping an eye on the clock. Obama and Romney each get two minutes to answer questions, a limit candidates are known to ignore.

It's a daunting task for everyone who faces it.

"It's the largest audience that you're going to play to, but there's also risk," says Tom Brokaw, who moderated the 2008 town hall-style debate and came in for some criticism afterward. "Candy should get combat pay."

Simpson says she was a "nervous wreck" before her appearance in 1992. In an interview with Jim Lehrer posted on the CBS website, Bob Schieffer recalled "literally shaking" before he moderated his first debate in 2004, even though he had been doing television for years. (Schieffer will moderate the final presidential debate next week.)

"She has a pretty big role in terms of shaping the content of that debate, just as the other moderators will," says Alan Schroeder, a Northeastern University professor and expert in televised debates. "She's a very no-nonsense person. She projects this skepticism. She's sort of seen it all, heard it all, and she knows — what's a polite word for B.S.? She knows prevarication when she sees it."

Crowley was selected to moderate the same format as Simpson, the first woman selected by the Commission on Presidential Debates in 1992.

Women were chosen as debate moderators in 1976, when debates were sponsored by the League of Women Voters, including PBS' Judy Woodruff and ABC's Barbara Walters. They served primarily as traffic cops directing responses to questions posed by a panel of journalists (both male and female) rather than asking questions themselves.

For Simpson, the town hall format was too much like being an emcee — the "lady with the microphone." She did not know what questions audience members planned to ask and she had little opportunity for follow-ups. Simpson is critical of Crowley being placed in that same role 20 years later.

"How much progress have we made?" she asks. "Yeah, the ladies can do the people in the audience, they're good at that, they're friendly and warm but the really hard stuff is going to come from the men. For the first time to have a woman come along in 20 years, to put her in that position I just think is sexist. I really do."

Crowley says she's fine with being the go-between for candidates and voters in a town hall setting. "I don't feel shut up," she says. "Would I love to sit down with (the candidates)? I would. But do I also realize there is benefit to seeing these guys on the big stage interacting with voters? I do. Let's roll with it and see what happens.''